Twitter is a great tool for all types of businesses, but every business should treat it differently.
What's Your Goal?
This should be the first question you ask yourself when starting a Twitter account for your business/brand.
What is my ultimate goal of investing my time (and sometimes money) into this Twitter account?
Let's go through some use cases and examples of how you can use it and then you can figure out what your ultimate goal is yourself.
Some Use Cases Of Twitter:
This is generally for businesses who already have a decent size following and userbase for their product. Often customers will use their Twitter account to tweet problems.
Are people talking 'about' you on twitter (not mentioning you). Engage them by monitoring the conversations with custom searches and joining in on the conversation.
It's a great way to get your content out and have people start spreading it. This should be a use case for EVERY twitter account used in combination with another method.
There is a good chance someone on the web is actually talking about the need your product is filling. On Twitter you can monitor these conversations and chime in:
It might be hard to find someone's e-mail who is high up in a certain industry. It's certainly not hard to find their Twitter accounts though. It's a great way to make an intial contact and build a relationship off of.
Great Tool: http://followerwonk.com/
You can also use Twitter to establish a unique voice that your customer will fall in love with.
Now figure out your growth strategy and start using Twitter with your goal(s) in mind!